The present invention relates to a polyethylene resin composition extremely superior in melt fluidity and more particularly to a polyethylene resin composition comprising an ethylene polymer and a fluorinated product of an ethylene-.alpha.-olefin copolymer having specific properties.
Polyethylene is widely used in various applications. Physical properties required of polyethylene differ according to uses, but moldability is an important physical property common to all applications. Good moldability permits increase of the molding speed and reduction of the power required for molding, thus leading to the improvement of productivity; besides, there will be obtained a molded article having a smooth surface, which leads to the attainment of a transparent film in the field of films.
In order to improve the moldability it is necessary to improve the melt fluidity of polymer. The fluidity can be evaluated by checking the shear rate - shear stress relation at the time of extrusion of a molten polymer from a capillary, or a shear rate (critical shear rate) at the time of occurrence of melt fracture. In general, where the fluidity of polymer is good, the critical shear rate (or stress) is high and melt fracture is difficult to occur.
Heretofore, for reducing the occurrence of melt fracture, there have been proposed methods such as, for example, the addition of various processing aids. In all of those methods, however, it is difficult to greatly or completely reduce the occurrence of melt fracture and so a further improvement has been desired.